The superintendent went into a roar of laughter. “Many’s the time I’ve heard Inspector Japp say that. M. Poirot and his little ideas! Too fanciful for me, he’d say, but always something in them.”

“You mock yourself at me,” said Poirot, smiling; “but never mind. The old ones they laugh last sometimes, when the young, clever ones do not laugh at all.”

And nodding his head at them in a sage manner he walked out into the street.

He and I lunched together at an hotel. I know now that the whole thing lay clearly unravelled before him. He had got the last thread he needed to lead him to the truth.

But at the time I had no suspicion of the fact. I overestimated his general self-confidence, and I took it for granted that the things which puzzled me must be equally puzzling to him.